Celebrities have been asked to check their facts before lending support to scientific research and campaigns, rather than risk misleading people.

Some celebrity-backed campaigns have done more harm than good, such as linking the MMR jab to autism, says the charity Sense About Science.

The group has listed statements made by stars on topics such as organic food, pesticides and ways to avoid cancer.

It adds scientists' views on whether the claims are misleading.

The list is contained in a pamphlet which is being distributed to VIP clubs and restaurants across the UK, as well as management agencies and publishers.

It offers advice such as "if it sounds too good to be true, it usually is", and lists a phone number for concerned celebrities to call if they want to discuss anything with experts.

'A fair bit of nonsense'

Sense About Science director Tracey Brown told BBC Radio 4's Today programme the claims made ranged from "the weird and the wacky" to more serious issues.

Scientists, traditionally a quiet bunch, are now trying to redress the balance and finding ways of promoting fact over misinformation

Illusionist Derren Brown

"There is a real problem when people present things as though they are scientifically grounded," she said.

"There is always going to be a fair bit of nonsense around, and particularly with the big interest in lifestyle."

Ms Brown added: "We are saying, 'Before you go public, check your facts'. All it takes is a phone call to us.

"We have over 1,400 scientists who are committed to helping improve public debate.

"We also have many of the medical research charities and the scientific societies who would much rather have a phone call and spend a bit of time than have to chase after trying to undo some misinformation to the public."

One celebrity who is backing the campaign is illusionist Derren Brown. He said: "We are more than aware that the media prefer a shocking story over delicate fact.

"In areas like food, environment and medicine, this can have serious results," he added.

"Scientists, traditionally a quiet bunch, are now trying to redress the balance and finding ways of promoting fact over misinformation."

In November, Lord Rees, president of the Royal Society, called on the scientific community to become more involved in public debates about their research.

He added that there was a tendency for minority "strident" views to get exaggerated, leading to an unbalanced debate.

Professor John Toy of Cancer Research UK said: "Celebrities often have a real effect on how members of the public view particular issues, especially health and lifestyle.

"They have a major responsibility, therefore, to be well informed before they make statements endorsing particular treatments of products so as not mistakenly to mislead people."